Автор: Philip Winston
Скрипт показывает эффект эластичного перемещения небольших картинок по экрану. В данном примере, в качестве картинок используются небольшие шарики, изображающие привязанную к курсору эластичную нить.
<BODY> <div id="dot0" style="position: absolute; visibility: hidden; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <div id="dot1" style="position: absolute; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <div id="dot2" style="position: absolute; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <div id="dot3" style="position: absolute; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <div id="dot4" style="position: absolute; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <div id="dot5" style="position: absolute; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <div id="dot6" style="position: absolute; height: 11; width: 11;"><img src="bullet.gif" height=11 width=11></div> <SCRIPT LANGUAGE="JavaScript"> <!-- Begin var nDots = 7; var Xpos = 0; var Ypos = 0; var DELTAT = .01; var SEGLEN = 10; var SPRINGK = 10; var MASS = 1; var GRAVITY = 50; var RESISTANCE = 10; var STOPVEL = 0.1; var STOPACC = 0.1; var DOTSIZE = 11; var BOUNCE = 0.75; var isNetscape = navigator.appName=="Netscape"; var followmouse = true; var dots = new Array(); init(); function init() { var i = 0; for (i = 0; i < nDots; i++) { dots[i] = new dot(i); } if (!isNetscape) { // I only know how to read the locations of the // <LI> items in IE //skip this for now // setInitPositions(dots) } for (i = 0; i < nDots; i++) { dots[i].obj.left = dots[i].X; dots[i].obj.top = dots[i].Y; } if (isNetscape) { startanimate(); } else { // let dots sit there for a few seconds // since they're hiding on the real bullets setTimeout("startanimate()", 3000); } } function dot(i) { this.X = Xpos; this.Y = Ypos; this.dx = 0; this.dy = 0; if (isNetscape) { this.obj = eval("document.dot" + i); } else { this.obj = eval("dot" + i + ".style"); } } function startanimate() { setInterval("animate()", 20); } function setInitPositions(dots) { var startloc = document.all.tags("LI"); var i = 0; for (i = 0; i < startloc.length && i < (nDots - 1); i++) { dots[i+1].X = startloc[i].offsetLeft startloc[i].offsetParent.offsetLeft - DOTSIZE; dots[i+1].Y = startloc[i].offsetTop + startloc[i].offsetParent.offsetTop + 2*DOTSIZE; } dots[0].X = dots[1].X; dots[0].Y = dots[1].Y - SEGLEN; } function MoveHandler(e) { Xpos = e.pageX; Ypos = e.pageY; return true; } function MoveHandlerIE() { Xpos = window.event.x + document.body.scrollLeft; Ypos = window.event.y + document.body.scrollTop; } if (isNetscape) { document.captureEvents(Event.MOUSEMOVE); document.onMouseMove = MoveHandler; } else { document.onmousemove = MoveHandlerIE; } function vec(X, Y) { this.X = X; this.Y = Y; } // adds force in X and Y to spring for dot[i] on dot[j] function springForce(i, j, spring) { var dx = (dots[i].X - dots[j].X); var dy = (dots[i].Y - dots[j].Y); var len = Math.sqrt(dx*dx + dy*dy); if (len > SEGLEN) { var springF = SPRINGK * (len - SEGLEN); spring.X += (dx / len) * springF; spring.Y += (dy / len) * springF; } } function animate() { var start = 0; if (followmouse) { dots[0].X = Xpos; dots[0].Y = Ypos; start = 1; } for (i = start ; i < nDots; i++ ) { var spring = new vec(0, 0); if (i > 0) { springForce(i-1, i, spring); } if (i < (nDots - 1)) { springForce(i+1, i, spring); } var resist = new vec(-dots[i].dx * RESISTANCE, -dots[i].dy * RESISTANCE); var accel = new vec((spring.X + resist.X)/ MASS, (spring.Y + resist.Y)/ MASS + GRAVITY); dots[i].dx += (DELTAT * accel.X); dots[i].dy += (DELTAT * accel.Y); if (Math.abs(dots[i].dx) < STOPVEL &&Math.abs(dots[i].dy) < STOPVEL &&Math.abs(accel.X) < STOPACC &&Math.abs(accel.Y) < STOPACC) { dots[i].dx = 0; dots[i].dy = 0; } dots[i].X += dots[i].dx; dots[i].Y += dots[i].dy; var height, width; if (isNetscape) { height = window.innerHeight + document.scrollTop; width = window.innerWidth + document.scrollLeft; } else { height = document.body.clientHeight + document.body.scrollTop; width = document.body.clientWidth + document.body.scrollLeft; } if (dots[i].Y >= height - DOTSIZE - 1) { if (dots[i].dy > 0) { dots[i].dy = BOUNCE * -dots[i].dy; } dots[i].Y = height - DOTSIZE - 1; } if (dots[i].X >= width - DOTSIZE) { if (dots[i].dx > 0) { dots[i].dx = BOUNCE * -dots[i].dx; } dots[i].X = width - DOTSIZE - 1; } if (dots[i].X < 0) { if (dots[i].dx < 0) { dots[i].dx = BOUNCE * -dots[i].dx; } dots[i].X = 0; } dots[i].obj.left = dots[i].X; dots[i].obj.top = dots[i].Y; } } // End --> </script>
